TreeView is in TabItem of TabControl with IsContentPreserved = False. On ContextMenu open and when working with Contextmenu, the underlying RadTreeViewItem is in MouseOverState. Changing tabs then back to the tab with the TreeView. When working with contextmenu, the underlying treeviewitem is not is mouseoverstate. Could be reproduced in CustomContextMenu QSF sample. Not reproducible in AddRemoveDisable sample.
The workaround is to set IsContentPreserved to true on the RadTabControl.